Atypical chemokine receptor 4 (ACKR4/CCRL1/CCX-CKR) binds and scavenges the ligands of the chemokine receptors CCR7 and CCR9 (CCL19/CCL21 and CCL25, respectively) and targets them for subsequent lysosomal degradation [PMID: 10706668, PMID: 16791897]. Apart from being a scavenger for chemokines, it may prevent CXCR3-induced chemotaxis by heteromerisation [PMID: 23121557]. ACKR4 appears to have a mayor role in normal thymus development and function [PMID: 25521433].